The Republican Party’s fragile control of the state Senate suffered a blow Tuesday when one of its Long Island members abruptly announced his resignation — effective immediately.

Sen. Charles Fuschillo, 53, a 15-year Senate veteran representing the Eighth District, made the bombshell announcement on New Year’s Eve in a time-honored attempt to minimize bad news.

Fuschillo was a popular incumbent who easily won re-election in 2012, although President Obama handily carried his district, 56 percent to 43 percent over Mitt Romney at the top of the ticket.

Senate Democratic sources are licking their chops, saying they have a good chance of stealing the seat with Fuschillo out of the way.

Another Long Island GOP senator, Lee Zeldin, is also departing to run for Congress. His seat also will be up for grabs.

As it is, the Republicans have been able to cling to power only through a power-sharing agreement with renegade Democrats.

With Fuschillo gone, there are now only 29 Republicans and 33 Democrats.

But four Democrats have formed an independent caucus and are part of the GOP majority coalition. Another conservative Democrat, Brooklyn’s Simcha Felder, caucuses with the GOP.

Gov. Cuomo will decide whether to call a special election within the next 60 days — allowing party bosses to nominate the candidates — or wait until the September primaries.

There are seven other vacancies that have to be filled.

“I am at point in my life where I am ready for a new challenge,” said Fuschillo, who will become CEO of the Alzheimer’s Foundation of America.

“This is a new and exciting opportunity which will allow me to continue to help improve the lives of others while at the same time enabling me to spend more time with my family.”

Sources close to Senate GOP leader Dean Skelos insisted he was not blindsided by Fuschillo’s move. The outgoing senator had wanted to jump to the private sector for some time, they said. Senate GOP sources insist they will run a strong candidate and keep Fuschillo’s seat.

“Chuck is a good friend and colleague and he will be missed,” Skelos said. “Sometimes in life, we are presented with opportunities that are simply too good to pass up. This is one of those moments.”